I am not a doctor but I have been around the block (I'm old) and have been involved with people dealing with their loved one's in a coma several times. I am of the belief that when a coma is involved that the answer to your questions is yes. Yes, family, friends etc. Can be helpful to the ill person. Talk to them as if they are capable of hearing (who says they are not). Tell them that you care for them and are waiting from them to wake up. Do this every time you enter the room. Do not talk negative talk where she might hear.
I, personally, brought my dearest friend out of a coma by speaking harshly to her and saying, "Mary, this is enough of your sleeping while I am here. Open you eyes and do it now!" Honest to goodness, she opened her eyes and gave me such a go to === look and then patted my hand. From that moment there was improvement until she was finally able to go home. It was amazing to me. We had been so nice to her for a long time, hugging, speaking gently, telling her we loved her, anything that we thought might bring her around. What it took was someone to break trough her subconscious with a demand. At least that is what we decided later on. Try it, what have you go to loose? Tell her family first so that they will know what you are attempting to do. Good Luck and say a prayer before you make this attempt.
I, personally, brought my dearest friend out of a coma by speaking harshly to her and saying, "Mary, this is enough of your sleeping while I am here. Open you eyes and do it now!" Honest to goodness, she opened her eyes and gave me such a go to === look and then patted my hand. From that moment there was improvement until she was finally able to go home. It was amazing to me. We had been so nice to her for a long time, hugging, speaking gently, telling her we loved her, anything that we thought might bring her around. What it took was someone to break trough her subconscious with a demand. At least that is what we decided later on. Try it, what have you go to loose? Tell her family first so that they will know what you are attempting to do. Good Luck and say a prayer before you make this attempt.